Health experts have warned against cuts to public health funding and social care as George Osborne announced a £3.8 billion cash injection for the NHS.
The funding boost - above inflation - for frontline NHS services in England has been warmly welcomed but experts said the cash must not be clawed back from other areas.
The Treasury has agreed the new settlement as part of a manifesto promise to give the NHS an extra £8bn a year by 2020.
It will bring spending to £106.5bn in 2016-17, which is the equivalent of a 3.7% or £3.8bn rise.
By 2020-21, the total budget will be £119.6bn - a rise of £8.4bn once inflation is taken into account.
But some critics have suggested that public health budgets still face cuts. These are held by councils for services including sexual health, stop smoking clinics and student nurse bursaries.
Doubts also remain over social care, which has a knock-on effect on the NHS. There has been a rise in the number of medically fit people having to stay in hospital because social care services are not available in the community for them to be discharged.
The numbers receiving social care is also falling, which critics argue increases the pressure on the health service.
Rob Webster, chief executive of NHS Confederation, welcomed the extra cash for the NHS but said "we are clear that significant risks remain".
He added: "In particular, the NHS will fail to deliver good care without adequate social care provision and improvements in the public's health.
"Local government budgets have been cut dramatically over the last five years and there is no doubting the knock-on impact this has on the NHS.
"If the funding gap in social care is not adequately addressed, costs will be shifted to health and if we don't use resources to keep people healthier for longer, we store up trouble for the future."
Anita Charlesworth, chief economist at the Health Foundation, said: "Make no mistake, the NHS is in the midst of an unprecedented financial crisis.
"Key targets for waiting times targets are being missed. There is deep concern about the quality of mental health services. Three-quarters of trusts are in deficit. NHS providers are expected to end the year £2.2bn in the red.
"To stop this decline the health service needs the pledged budget increases to arrive sooner rather than later and the Government's confirmation of front-loaded funding is therefore welcome.
"However, any move to redefine and shrink the definition of the NHS would be particularly worrying.
"If some of this new money comes from other parts of the health service - such as public health or training - it would be a false economy and likely to have a negative impact on service and efficiency.
"Even with additional funding this will be the most austere decade for the NHS since its inception. Public funding for the NHS will fall as a share of GDP from the current 7.4%.
"The UK already devotes a lower share of its economic wealth to health than most other European countries such as Germany, France and the Netherlands."
Mr Osborne - who is due to unveil full details of his Comprehensive Spending Review alongside his Autumn Statement on Wednesday - said the extra money, which includes cash already given to the service, would mean world-class treatment for patients.
He said: "We promised the British people that their priority was our priority, and we would fund our National Health Service.
"We will deliver £6 billion a year extra investment straight away, as those in charge of the NHS have requested.
"This means I am providing the health department with a half a trillion pound settlement - the biggest ever commitment to the NHS since its creation.
"This will mean world-class treatment for millions more patients, deliver a truly seven-day health service and allow the NHS to implement its five-year plan to transform the services patients receive."
The Government has pledged that by 2020 everyone in England will be able to access GP services in the evenings and at weekends.
By the same time, all key hospital services are due to operate seven days a week.
Figures released on Friday showed that NHS trusts in England have racked up a deficit of £1.6 billion in the first six months of the financial year - the worst on record.
Based on current performance, trusts are predicting they will end the financial year £2.2 billion in debt, with 156 out of 239 of them recording deficits, the regulator Monitor said.
The figure has soared above the £820 million overspend for the entire previous year.
The £1.6 billion overspend is also £358 million more than planned for at the start of the year.